270deg oil temps w/Redline..should I worry?

[Al]

quote:

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Originally posted by userfriendly:
Al, You seem to know quite a bit about engine oils. Is 287F not a little high for conventional engine oils especially ones with VI improver in them?
I thought that after 250F dino oils go all to heck in a hand bag in a hurry.

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Thanks for the compliment-but compared to some others on this board I'm pretty weak. But petroleum oils double in rate of oxidation about every 18 degrees over 150F. You are right at 250F oil life goes by fairly quickly. And its a good question as to how fast an oil without any Group III, IV, or V would go totally south at this temp. I sure don't know that answer.

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[buster]

Al, You seem to know quite a bit about engine oils. Is 287F not a little high for conventional engine oils especially ones with VI improver in them?
[/QUOTE

You know more then I do, thats for sure.

[ September 26, 2003, 07:54 PM: Message edited by: buster ]

 

[TooSlick]

Tyrolkid,

As Ken mentioned, the main drawback to running very high engine temps is reduced seal and gasket life.

I'd look at the freeze points of 40%/60% and 30%/70% mixtures of EG/Water. As you know, water has a significantly higher specific heat than does Ethylene Glycol, so if you run a higher percentage of water it will lower your bulk coolant/engine temps.

I have a customer I met up at the Oshkosh Airshow several years back that was having a similar problem. He is running a Cadillac Northstar V-8 engine in an experimental composite airplane and regularly sees oil temps in the 260F-280F range.

If you run a lower percentage of coolant you'll want to change it more often, but that's no big deal for someone who turns wrenches anyway ....

TS

 

[Tyrolkid]

Thanks for the posts guys! Awesome stuff.

The exhaust is 3" with a dump tube in race mode. It's 3">>>2.5" in street mode.

I agree with the statement about cam gears not ultimately increasing power, but shifting the complet power curve either up or down.

As far as exhaust gas pressure being higher than boost pressure, this could indeed be true, leading to contamination of the incoming charge. I also agree that increasing intake duration might help that, but since I left my $100k cam-grinding machine at home today, I have no way of making one in the office

I'm not worried about seal life at this point as I'm having too much fun driving the heck out of this car.....

 

[userfriendly]

For about $100.00 you could get the stock cams re-ground.
The best way, would be to find a couple of stock cores that someone else has taken out of their engine so you don't have to take your car out of service.
Lets play with some numbers:
Say for example your cams are 220 degrees at .050" and are installed at a 110 degree lobe seperation.
Your .050" timing figures will be I 0/40, E 40/0.
If you had 20 degrees of duration added to your cams, to 240/240 without changing the 110 lobe seperation, the .050" timing would be:
I 10/50, E 50/10.
Instead of having 0 degrees of overlap at .050"
you now would have 20 degrees of overlap, which will cause cross contamination, exhaust gasses diluting the intake mixture, and reverse flow of the exhaust gasses during high boost conditions.
The larger cams would help top end hp and hurt low-end power and drivability.
However if you took those 240 degree cams and installed the intake cam 10 degrees retarded, and the exhaust cam 10 degrees advanced, your .050" timing figures would be:
I 0/60 E 60/0.
The overlap figures are back to stock, along with your low-end power and drivability, with a much larger cam, as lobe seperation is now 120 degrees instead of 110 degrees.

[ September 29, 2003, 06:15 PM: Message edited by: userfriendly ]